Background The porcine model has been used in several preclinical contexts due to its anatomical and physiological homology with the human body. Here, we focus on the utility of the porcine knee in replicating human joint anatomy. Previous studies have identified the porcine stifle joint to have similarities to human with respect to the ACL, PCL, menisci, femoral condyle width, tibial plateau and interspinal width, and bone mineral density. However, there is mixed data on advantages of respective porcine breeds, sizes, and ages. This study aims to support existing data on the use of porcine knees for orthopedic research as well as add a new perspective on the use of adolescent porcine knees as an analogous preclinical model.

Methods Yorkshire pigs aged 1-3 months were used to obtain sixty porcine stifle joints, which were dissected and analyzed for femur and tibia dimensions as well as medial and lateral meniscal height, width, and volume. Measurements were obtained via digital vernier caliper (precision of 0.01mm) and ImageJ extrapolation from standardized photographs. Scaling was performed with a reference ruler to ensure appropriate pixel-length ratio. Comparative analysis to human data was performed via PubMed literature search. Reliability was assessed with Intraclass Correlation Coefficients and unpaired Student's t-tests.

Results Joint measurements showed a mean of 64.67±4.12mm for medial femur AP width, 63.54±3.67mm for lateral femur AP width, and 61.73±3.23mm for femur medial-lateral width. The mean medial tibia AP width was 43.15±3.10mm, lateral tibia AP width was 40.07±2.17mm, and tibia medial-lateral width was 63.60±3.81mm. Compared to human measurements, this data in aggregate shows a 0.86 correlation coefficient, demonstrating a strong positive correlation between porcine and human anatomy. Additionally, the femoral intercondylar notch dimensions widened and became shallower with age, resembling the maturation patterns seen in human knee development. For menisci measurements, there were notable differences between the medial and lateral measurements, with medial menisci averaging 13.31±1.86mm in width and lateral menisci at 15.38±1.9mm. The meniscal volumes, recorded at 4.30±0.13ml for medial and 5.9±0.29ml for lateral menisci, aligned closely with those reported in human studies, reported as 4.5ml and 5.0ml, respectively.

Conclusion This investigation confirms that the porcine stifle joint closely mirrors human knee anatomy and additionally suggests that adolescent porcine samples may be used in preclinical orthopedic research. The identified age-related morphological variations further refine model selection, enhancing orthopedic research value. This information supports the porcine model as cost-effective and accessible for knee, ACL, and meniscus research.